Field of the Invention
The present invention relates to shavers and more specifically to shavers capable of adapting in use to improve the shaving effect. The invention applies to shavers having both stationary and moveable cutting elements and further relates to methods of operation of such devices.
Description of the Related Art
In shaving it is of interest to control the engagement of a cutting element with the skin to achieve the best and most consistent shaving experience whilst maintaining safety and comfort. The degree to which the skin bulges ahead of a blade or cutting element is termed doming. Increasing the shaving pressure may improve the shaving closeness but can also increase doming. As doming increases, the likelihood that the cutting element will damage the skin also increases. The doming of the skin in a shaving system is therefore of fundamental importance to a shaving experience.
Skin doming for a particular shaving system depends on the system geometry and materials used. It additionally varies due to changes in shaving pressure, speed, direction, area of the body and individual variation of a person's skin properties. There is thus considerable variation in terms of the risk of cutting and the shaving closeness that can be achieved without damaging skin or causing discomfort.
In wet shaving, skin doming is generally controlled by adding a rubbery skin stretcher that increases skin friction. This is located in front of the cutting element, the wet-shaving razor usually having one clear direction of use over the skin. By stretching the skin taut, its ability to dome ahead of the cutting element or blade is reduced. A lubricity strip may also be placed behind the cutting element or blade, which further enhances the stretching effect on the skin. Devices have also been proposed that actively seek to stretch the skin as described in EP1697095.
In dry shaving, the shaver is frequently moved in multiple directions over the skin. This means that in rotary dry shaving or in linear foil electric shaving the guard or skin engaging surface is limited by having to allow for movement over the skin in any direction.
A skin stretching solution of the type used in wet shaving systems is therefore not possible. In certain designs, the guard member (a foil or a shaving cap) or a skin engaging surface of the shaving head may be provided with stretching elements in the form of rings or protrusions which assist in supporting the skin and controlling the pressure and angle at which it comes into contact with the cutting element. A rotary shaver provided with a skin stretching element is disclosed in WO02051598.
It would therefore be desirable to provide a shaver that allowed better control of skin doming irrespective of the direction of movement of the shaver across the skin.